Adjustable thimble



FIG. 1 is a top perspective view of an adjustable thimble showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a left end elevational view thereof; and

FIG. 6 is a right end elevational view thereof. 

The ornamental design for an adjustable thimble, as shown and described. 